Next, to assess the effect of boosting vaccination- or infection-induced T-cell responses by mRNA vaccination on the spike-specific CD8+ T-cell repertoire, we again used overlapping spike peptides to map spike-specific CD8+ and CD4+ T-cell responses in longitudinally followed vaccinees getting their third vaccine dose (Pfizer/BioNTech mRNA vaccine; n = 7; Supplementary Table 1) and convalescent individuals who received an mRNA booster vaccination (n = 3; Supplementary Table 1). Here, CD4 is linked to infection.